title: Determination of trimethoprim in tissues using liquid chromatography-thermospray mass spectrometry.
abstract: A method is described for the determination of the antibacterial drug trimethoprim in tissues. Minced tissue is homogenised with chloroform-acetone (1 + 1 v/v), filtered, and the filtrate evaporated to an oily residue using a rotary evaporator. The residue is redissolved in methanol-water-acetic acid (50 + 48.7 + 1.3 v/v) and any fats present are partitioned into hexane. The aqueous phase is analysed by liquid chromatography-thermospray mass spectrometry in positive mode with the protonated molecular ion at m/z 291 being monitored. Recoveries ranged between 60% in liver and 79% in muscle. The limit of determination was 25 micrograms kg-1 and the limit of detection was approximately 4 micrograms kg-1. The method is suitable for monitoring tissues taken under national surveillance schemes for veterinary drug residues.
authors.affiliation: Veterinary Sciences Division, Department of Agriculture for Northern Ireland, Belfast, UK.
authors.forename: A
authors.initials: A
authors.lastname: Cannavan
authors.forename: S A
authors.initials: SA
authors.lastname: Hewitt
authors.forename: S D
authors.initials: SD
authors.lastname: Floyd
authors.forename: D G
authors.initials: DG
authors.lastname: Kennedy
mesh_terms: D000818:Animals; D000892:Anti-Infective Agents, Urinary / Q000032:analysis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004350:Drug Residues; D005506:Food Contamination; D007668:Kidney / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D018482:Muscle, Skeletal / Q000737:chemistry; D014295:Trimethoprim / Q000032:analysis* / Q000737:chemistry
chemical_list: D000892:Anti-Infective Agents, Urinary; D014295:Trimethoprim